Purely for safety purposes, flame retardants or flame resistance of a fabric is a highly desirble characteristic. Of many methods available for developing various levels of flame retardance all possess a variety of disadvantages, the principal ones being the inability of the flame retardant material, or treatment, to last through laundering or dry cleaning operations. Another principal disadvantage of treatment of fabrics to develop this characteristic of flame retardance is the loss of hand in the substrate. The problem is greatly aggravated in some areas of handling, particularly where it is necessary to meet regulatory, including statutory, requirements for flame retardance in garments. Their physical condition being in the form of a bundle of fine fibers invites and encourages the sustenance of a flame if one gets started in the fabric. That is, a large area of oxidation is presented to any flame which gets started.
Flame retardants for textiles and related materials of the durable type have been found to possess a multitude of side effects that would either render the flame retarded substrate unusable or reduce its useful life. In addition, most commonly used methods will be effective on one particular substrate while completely ineffective on others or blends of the same.
Flame retardant fabrics are worn by workers exposed to hot molten metals, glass and other compositions in the metals, glass and related industries and employed, for example, in steel mills, non-ferrous metal foundaries, welding and the like. Normally heretofore, the fabrics used in the manufacture of garments to be worn by workers in the metals industries are one hundred percent cotton and rendered flame retardant with phosphorus containing compositions, such as tetrakis hydroxymethyl phosphonium chloride, tetrakis hydroxymethyl phosphonium sulfate, and n-hydroxymethyl-3-(dimethylphosphono)propionamide (e.g. that sold under the trade name PYROVATEX CP by Ciba-Geigy Corporation).
It has been found, however, particularly where persons come into contact with non-ferrous metals in the molten state, such for example, as in non-ferrous metal foundaries, that the presence of the organo-phosphorus compounds on the fabric of workers' clothes causes or promotes adhesion of molten metals to the fabric. Due to the flame retardant character of the fabric effected by the presence of the organophosphorus flame retardant composition, the fabric does not usually ignite of burn when, by way of illustration, it is sprayed with molten metal or molten glass. The adhesion of the molten metal to the fabric results, however, in frequent material discomfort, in the form of severe burns and blisters.
It is, accordingly, a basic objective of this invention to provide a method employing familiar techniques in the textile industry for the application of flame retardant materials to textile fibers, whether the fibers be in the form of woven or non-woven cloth, knitted cloth or in the form of thread or fibers prior to being woven into the cloth.
It is a more particular object of this invention to provide flame retardant compositions for use in protective fabrics and fibrous compositions that will not only fail to ignite when brought into contact with hot, molten metals and materials including silicates of metals, such as glass, as for example, by splashing or spraying of the fabric with molten materials, but will not cause the molten metals to adhere to the fabric; and, indeed, will tend to repel the projected metal.
Other objects and advantages of the invention will be apparent from the description appearing hereinafter.